look at it from a business perspective if you already have half the App using world purchase your app and you already update it pretty regularly (with they do) they if your offering a huge expansion (which 45 levels is) it makes more sense to put out a new app and charge the $.99 to use this allows you to double your profits and only let use to those who are really dedicated.

not to mention that your business isn't going to effect them. in 6 days they sold 1,000,000 copies so using the 70/30 split from apple they made $700,000 off this one app.

and having sold 3.5 million copies of the original app that $700,000 + $2,450,000